Comprehensive Evaluation Of Cu Tolerance And Differences Of Gsh Metabolic In Different Wheat Cultivars

In this study,a hydroponics experiment was conducted to study the genotypic differences of wheat cultivars to Cu stress and their Glutathione metabolism to elucidate the mechanism of anti-oxidative response under Cu stress.Thirty-seven wheat cultivars were selected and exposed to 30 mg·L^-1Cu²⁺stress in this experiment.The mainly research results were as followed.1.Six growth and physiological indexes including root length,plant height,root activity,total root length,root volume and root surface area in young roots were measured,and a comprehensive evaluation for wheat Cu resistance was achieved through correlation analysis,subordinate function analysis and median clustering method.Thirty-seven cultivars were classified into three groups after they were exposed to Cu for 48 hours.The high Cu resistant group was consisted of 11 varieties including Liangxing 99 and Jimai 22.The medium Cu resistant group was made up of 8 cultivars,such as Shiyou 17 and Shiyou 20.Eighteen varieties such as Xinong 979 and Luomai 23 belonged to the weak Cu resistant group.And all wheat cultivars were classified into three groups as they were exposed to Cu for 96 hours.The high Cu resistant group was consisted of 7 varieties including Liangxing 99 and Jimai 22.The medium Cu resistant group was made up of 22 cultivars,such as Zhongmai 1 and Shinong 952.Eight varieties such as Xinong979 and Luomai 23 belonged to the weak Cu resistant group.2.Jimai 22 and Luomai 23 that exposed to Cu for 48 hours were sequencing by transcriptomic sequencing.The results revealed that 49,611 and 43,195 genes were detected in Jimai 22 and Luomai 23,respectively.After its parameters were adjusted as FDR P≤0.01,fold change≥2,we found that these differentially expressed genes were widely enriched in different antioxidant pathways including sustances reacting and oxidation resistance by function analysis of GO.To further investigate the glutathione mechanism,we analyzed their KEGG pathway,and we found 26 and 17 up-regulated genes involved in glutathione metabolism in Jimai 22 and Luomai 23 respectively.It was interesting to find that 8 of the 13unique genes in Jimai 22 encoded GSTs,which might indicate that the resistance to Cu of Jimai 22 was related to the number of genes that encoded GSTs.3.The relative expression levels of 10 genes which detected by qRT-PCR were compared with the sequencing results of transcriptome through the commonly used 2^-⊿⊿Ctmethod.It was found that the tendency of qRT-PCR were consistent with that in transcriptome datas,therefore the transcriptome datas obtained in this study were reliable.4.The results showed that the three glutathione-related enzyme activities were quite different between Luomai 23 and Jimai 22.And with the prolongation of Cu stress time,the enzyme’s activities were also varies.The activity of GSTs in Luomai 23 was significantly higher than that in Jimai 22 under Cu stress for 48 hours or 96 hours,and there was a significant positive correlation between GSTs activity and GSH content.The activity of GR in Jimai 22 was higher than that in Luomai 23 under Cu stress.GSH-PX activity in Luomai 23 was higher than that in Jimai 22 when they were exposed to Cu for 48 hours,while it was higher in Jimai 22 compared with that in Luomai 23 after they were exposed to Cu 96 hours.5.With the prolongation of Cu stress time,the concentration of Cu in young roots of Jimai 22 and Luomai 23 increased significantly,and Cu content in Luomai 23 was higher than that in Jimai 22.GSH concentration was higher in Luomai 23 than that in Jimai 22 when they were exposed to Cu for 48 hours or96 hours.Compared with the Control group,GSH concentration in samples that exposed to Cu for 96 hours was higher,which was opposited to that under 48 hours.